This invention relates to a process for the production of poly(polyisocyanate-alkali metal silicate) products by reacting an isocyanate compound containing 2 or more isocyanate radicals and powdered alkali metal silicate glass.
The products produced by this process may be quite varied in physical properties; they may be pre-polymers, solids, porous, rigid or elastomine, and the porous products may be rigid or soft and flexible and be an improvement over previously produced polyisocyanate-alkali metal silicate products.
It is known in the Arts that polyisocyanates with aqueous sodium silicate and/or polysilicic acid will react to produce products. The process of this invention has an advantage over previous processes in that no other compound such as water, amine catalyst, organic tin catalyst other organic compounds, etc., are not necessary to produce good foamed products. Another advantage is that alkai metal silicates that contain much less alkali metal oxide radical and are not water-soluble may be used in this process, thereby lowering the cost of the alkali metal silicate component. Another advantage is that the use of alkali metal silicate glass with low amounts of alkali metal oxide radicals improves the physical properties of the foamed results produced by decreasing or eliminating the tendency of foams which contain large amounts of the alkali metal oxide to absorb moisture from the atmosphere. Another improvement is that when aqueous alkali metal silicate solutions or hydrated alkali metal silicates are reacted with polyisocyanates, the water present reacts first with the polyisocyanate, thereby producing a different foamed product containing polysilicic acid. When an excess of water is present, the polysilicic acid reacts only with the water and does not react with the silicate radical, but instead, the polyisocyanate-water reaction produces carbon dioxide which reacts with the alkali metal silicate compound to produce polysilicic acid and alkali metal carbonate. When polyisocyanate is mixed with a powdered alkali metal silicate glass, the chemical reaction is catalyzed by the alkali metal oxide radical and the polyisocyanate radical reacts with the alkali metal silicate, therby giving off carbon dioxide which reacts with some of the alkali metal oxide radical to produce alkali metal carbon and producing a foamed poly(polyisocyanate-alkali metal silicate) product. The exact chemical reaction that takes place is not known.